Airplane Landing Questions -- How can the pilot see the ground?

[russ_watters]

Is there any relationship between our breathing and airplane? I mean. For air dense enough to fill our lungs, the same air can lift wings.

Yes, that's more or less true.

Is it possible for biology to evolve such that we don't need such dense air to breath...

Yes, evidently the Nepalese have evolved to be better able to deal with lower air density than most people.

...and so can live without possibilities of any airplanes?

I can't parse that.

In a planet where airplanes can't exist. Then I guess most have to travel by boat only. Is it not. Or can rocket engines as transportation work without airfoil technology too?

Rocket engines work best where there is no air at all.

 

[seazal]

Just wondering about this. Is it allowable in airport to bring parachute in bag pack? (for those who have phobia about airplane crashes who would like to bring parachute just in case)?

And for those learning to fly small airplane (with or without propellers). Can't you use or deploy parachute during emergency? This is a reasonable safety device and question.

 

[Baluncore]

If you cannot trust the aircraft and the crew you should not be aboard.
Carrying a parachute onto a commercial flight is an indication of irrational behaviour.

 

[seazal]

If you cannot trust the aircraft and the crew you should not be aboard.
Carrying a parachute onto a commercial flight is an indication of irrational behaviour.

But is it illegal? What is the smallest parachute backpack one can bring onboard a commercial aircraft. What does aviation regulation actually says about this? Just asking.

 

[CWatters]

Just wondering about this. Is it allowable in airport to bring parachute in bag pack? (for those who have phobia about airplane crashes who would like to bring parachute just in case)?

Sure you can take one. However:

1) Airliners aren't designed for people to jump out of. The cabin is pressurised and the doors typically open inwards - so you can't easily open the doors to jump out.

2) Airliners can cruise at 35,000ft. If you jumped out at that height you would probably die unless you also had an oxygen system. Even if you free fall I don't think you can't get down fast enough to avoid suffocation.

3) If the aircraft is out of control you won't be able to get your chute out of the overhead, strap it on and casually walk to the door. You will most likely be experiencing very high g forces as the aircraft tumbles. If the aircraft is under control, why jump out of it? Far safer to stay in the aircraft.

4) Most accidents occur during take off or landing. You would have to be wearing your chute and stood by the open door waiting to jump just in case. And what if you can't jump because you are too low before realising there is a problem? You would be safer strapped into your seat.

5) Most of the planet is covered by ocean, ice, mountains, forests or deserts. How do you rates your chances of survival after jumping?

I'm sure there are lots of other problems.

And for those learning to fly small airplane (with or without propellers). Can't you use or deploy parachute during emergency? This is a reasonable safety device and question.

Many glider pilots do wear a parachute. Not many have ever had to use it but it makes the seat more comfortable.

You can buy ballistic recovery parachute systems for light aircraft but they do add weight and cost. Weight increases drag and fuel consumption. Its your choice. They have saved a few lives.

PS: In 2013 a group of parachutists died in Belgium when their plane developed a problem at 3000m (about 9000 feet). Only three managed to get out of the plane before it crashed and their chutes opened too low to save them.

 

[Klystron]

Please suggest books that answer these questions directly:

Before the Wright Brothers, what were the theories why birds fly? When was the airfoil technology or principles first discovered? And why were the Wright Brothers the first one to successfully apply it?

To study early understanding of bird flight search for biographies of Leonardo d'Vinci. Leonardo's sketches of birds were used for centuries. His drawings include many sketches of possible and impossible vehicles. The painter James Audubon continued the tradition of accurate images of birds. Please choose yourself from the many books on both painters.

Though generally associated with hot air balloons, the Montgolfier brothers studied flight before the Wrights. https://en.wikipedia.org/wiki/Montgolfier_brothers

This beginning aerodynamics tutorial is a starting point for NASA docs. https://www.grc.nasa.gov/www/k-12/airplane/bga.html

 

[Klystron]

The Wright brothers were successful for many reasons but IMO their design of a light-weight piston engine fueled by gasoline gave them just enough power-to-weight to enable controlled powered flight. As previously mentioned they also built scale-model wind tunnels to test designs. Their experience as bicycle mechanics helped design the fuselage and (later addition) undercarriage.

 

[seazal]

You've probably felt but were unaware of something called "Ground Effect"
when the plane gets about one wingspan above the ground, the air underneath it has to get squished out from under the wings
raising pressure on bottom side of the wings causing more lift.
Pilot will reduce power and raise the nose to increase drag and dump speed, encouraging the plane to continue on down to the ground..
https://en.wikipedia.org/wiki/Ground_effect_(aerodynamics)

Next time you fly
pick a window seat a row or two behind back edge of the wing.
Pay attention to what goes on as you get over the end of the runway-
As the plane descends toward the runway you'll see those big flaps move back and down changing the wing shape from flat to curved
trapping air underneath the wing as it gets ever closer to the runway.
On a warm humid summer day you'll see vapor trails curl around the flap edges as the air moves from high pressure region ahead of the flap to low pressure behind it, cooling as it goes...
Just watch and ask yourself "why" about everything you notice.He looks out the side window.

Jim. Why did you say "He looks out the side window" when I asked how the pilots can see landing strip with nose pointed up? I found out they could actually see the runaway. Check this out.

https://www.google.com/search?q=pilot's+view+landing+an+airplane&ie=utf-8&oe=utf-8&client=firefox-b-1

Yesterday I was surprised learning the pilots could still see the ground during landing. Is it not the nose is pointed upwards so the pilots shouldn't see the ground. I guessed prior to learning it they were all landing blind. But are there airplanes where they really land blind?

If you like aviation
i recommend reading Charles Lindbergh's "Spirit of St Louis"
he didn't have a forward view at all , only side windows...
the 1956 movie staring James Stewart is also very good, and is on Netflix

 

[OCR]

But is it illegal?

Maybe not illegal (?) ... but you would need to have a damn good reason.

Lol... and an even better story. .

.

 

[jim hardy]

I guessed prior they were all landing blind. But are there airplanes where they really land blind?

of course it depends on how the front of the plane is shaped
and if it's tricycle gear or taildragger

https://studentpilotnews.com/2017/06/09/video-pilots-eye-view-p-51-flight/

 

[seazal]

Maybe not illegal (?) ... but you would need to have a damn good reason.

Lol... and an even better story. .

.

Jump to 50 seconds of this video



You can see cracks forming in the fuselage (why does the crack formed and how often does it happen?) and the plane breaking apart in midair, so the passengers just fall down from the sky. If one wears a parachute, perhaps one can survive the fall?

 

[rcgldr]

Mars, it would take a very large and light airplane.

Or just a lot of speed. NASA has considered the use of gliders going fast enough for a reasonable glide ratio and duration of time before crashing to surveil the surface of Mars. Various prototypes have been tested by dropping them from weather balloons at high altitudes. Most of the gliders are autonomous, but switch to radio control like mode for controlled landings. Example article:

https://www.nasa.gov/centers/armstrong/features/whaatrr_glider.html

 

[seazal]

What units do you measure the density of air on earth? And can anyone share any calculations to support that airfoil principle is enough to lift millions of pounds (3.3 million pounds in case of the space shuttle)? It's somewhat hard to believe that mere air and even air pressure can support such weight. It looks like as thrust increases, the pressure increases. What formulas relate them.

 

[FactChecker]

The term autopilot seems slightly naive on an I-level thread.

I disagree. Even in modern fighters, there are modes in the flight control that are called "autopilot modes".

 

[FactChecker]

You've probably felt but were unaware of something called "Ground Effect"
when the plane gets about one wingspan above the ground,

Yes. It is noticeable if you pay close attention. It feels as though the plane slides forward a little faster just as it is about to touch down.

 

[CWatters]

https://www.tsa.gov/travel/security-screening/whatcanibring/items/parachutes

You may transport parachutes, either with or without Automatic Activation Devices, in carry-on or checked bags.

Parachutes should always be packed separately from other baggage. If a TSA officer determines that a bag must be opened to inspect the parachute, you must be present to assist in the inspection. If you are not within the screening area, you will be paged using the airport intercom system; if you are not present to assist with screening the parachute, the parachute will not be allowed on the plane. For this reason, passengers with parachutes are encouraged to add 30 minutes to the airlines' recommended arrival window. TSA is not responsible for repacking parachutes. All parachutes should be thoroughly inspected at their end destination to make sure that the equipment is still safe to use.

 

[CWatters]

You can see cracks forming in the fuselage (why does the crack formed and how often does it happen?) and the plane breaking apart in midair, so the passengers just fall down from the sky. If one wears a parachute, perhaps one can survive the fall?

In case it's not obvious that bit of the video is cgi. Aircraft almost never break up that slowly. They are pressurised so the forces on an area of a few square feet is very high. Think explosion not slow break up.

In an earlier post I listed several reasons why having a parachute is not likely to help. I could easily afford to buy one but taking one on a civilian airliner is a total waste of time.

 

[russ_watters]

Jump to 50 seconds of this video

You can see cracks forming in the fuselage (why does the crack formed and how often does it happen?)...

https://en.wikipedia.org/wiki/China_Airlines_Flight_611#Metal_fatigue_cracking

It was an improper repair from a previous incident that weakened the tail. It's not a common thing.

...and the plane breaking apart in midair, so the passengers just fall down from the sky. If one wears a parachute, perhaps one can survive the fall?

If they are already wearing the parachute and if the breakup of the plane doesn't kill them and if they are able to get out of whatever piece of the plane they are trapped in. If, if, if, if, if.

Of course, if they are in a crash on the ground, wearing the parachute could make it harder to escape the burning plane, making death more likely.

 

[russ_watters]

What units do you measure the density of air on earth? And can anyone share any calculations to support that airfoil principle is enough to lift millions of pounds (3.3 million pounds in case of the space shuttle)? It's somewhat hard to believe that mere air and even air pressure can support such weight. It looks like as thrust increases, the pressure increases. What formulas relate them.

I'm starting to wonder if you are really serious here or are just messing with us - pretending to be panicky and irrational. Surely you know the Space Shuttle flies into space over a cluster of rocket engines, not from aerodynamic lift, right?

This thread needs to become more serious, rapidly, or it will be closed.

 

[FactChecker]

What units do you measure the density of air on earth? And can anyone share any calculations to support that airfoil principle is enough to lift millions of pounds (3.3 million pounds in case of the space shuttle)? It's somewhat hard to believe that mere air and even air pressure can support such weight.

Air pressure can exert a huge force -- much more than required to hold up an airplane. A modern fighter easily performs maneuvers at G's up to 9. That is 9 times more than required to hold the plane up and it is all coming from air pressure. All that is needed from an engine to keep a plane up is enough thrust to stop the downward glide of the plane. That is not much.

 

[FactChecker]

Any airplane mishap is investigated like crazy. It's not like with car accidents, where they only pay attention after dozens or hundreds of crashes. Any crash will be investigated thoroughly for months or years if necessary. The only reason that is practical is that there are so few accidents.

 

[Klystron]

I disagree. Even in modern fighters, there are modes in the flight control that are called "autopilot modes".

Yes. My intended point was that autopilot functions can be modeled by distributed systems; modes of operation across a flight control grid connecting cluster . Not as a monolithic "on/off" device.

 

[jrmichler]

Air pressure can exert a huge force -

Stick your hand out the window of a car. Drive into a headwind at highway speed. Note the pressure when your hand is aligned with the airflow, and when your hand is perpendicular to the airflow. Compare the area of your hand to the area of a wing. Consider that aerodynamic forces are proportional to the square of the airspeed. Consider that your hand is not an airfoil.

Go to your nearest airport and pay for an introductory flying lesson. If it's in a single engine Cessna, ask for permission to open the window and stick your hand out. Single engine Cessna airplanes are allowed to fly with a window open, although it does get noisy.

 

[jim hardy]

What formulas relate them.

Force = Pressure X Area
Look up "Wing Loading"
https://en.wikipedia.org/wiki/Wing_loading

http://www.thespacereview.com/article/1880/1
shuttle is about 120 pounds per square foot
not too different from a modern airliner

http://www2.gvsu.edu/ramseyea/B17.html
WW2 B17 bomber about 60,000 pounds / 1420 sq ft = ~42 pounds per square foot

little private airplanes around 15 pounds per sq ft

monarch butterfly about 1/30th pound per square foot

 

[CWatters]

Jump to 50 seconds of this video



You can see cracks forming in the fuselage (why does the crack formed and how often does it happen?) and the plane breaking apart in midair, so the passengers just fall down from the sky. If one wears a parachute, perhaps one can survive the fall?

It exploded at 35,000 feet and about 25 miles from nearest land. Even if you survived the explosion you would also have needed ..

Previous lessons in how to free fall.
An oxygen system.
A boat.
A waterproof GPS.
A waterproof satellite phone.
Or an emergency locator beacon.

 

[jim hardy]

That China plane suffered a tail strike , that's where the tail drags the ground from a bad landing or takeoff.

PPRuNE talked about a 68 inch crack in underside of tail that was just patched over , might have failed depressurizing part of the plane and blew out a bulkhead.
I think that's what the official report concluded .
But i haven't read that report, just the thread at PPRuNE which is unofficial yet educational

 

[seazal]

I'm starting to wonder if you are really serious here or are just messing with us - pretending to be panicky and irrational. Surely you know the Space Shuttle flies into space over a cluster of rocket engines, not from aerodynamic lift, right?

This thread needs to become more serious, rapidly, or it will be closed.

I was talking about the Space Shuttle landing, not take off. Remember it lands like an airplane and takes off like a rocket.

I'm serious because whenever I fly 2 hours short trips I always give reminders to family of important matters like codes to the safe, etc. just in case. And next year I plan to take longer flight (maybe 10 hours) to Europe I hadn't tried before. So just want to gain more knowledge of it (it is said that to treat phobia, you need to face the fear or study it more).

An airplane depends on continuous thrust or it could stall and fall down, whereas all other vehicles like cars or boats can be stop anytime and you are safely at ground.

I'm now convinced parachute is not needed because of difficulty of deployment. So just need to trust the best airliner. There is now this Airbus 380-800 model which has two levels. It needs much more thrust and jet engine, so the question now is.. is it better to fly using smaller airplane that requires smaller or fewer jet engine or bigger airliner with jumbo jet engines. Which do you prefer guys?

 

[FactChecker]

An airplane depends on continuous thrust or it could stall and fall down,

If it lost total power, it would start gliding. It has a lot of time to get power again (except right at takeoff). Most commercial airplanes have several engines and can fly with fewer. The danger occurrences are few and far between. In fact, they are so rare that there will often be a TV show about any airplane crash like you are talking about. (Private airplanes are a different story. Those people are sometimes careless.)

 

[seazal]

If it lost total power, it would start gliding. It has a lot of time to get power again (except right at takeoff). Most commercial airplanes have several engines and can fly with fewer. The danger occurrences are few and far between. In fact, they are so rare that there will often be a TV show about any airplane crash like you are talking about. (Private airplanes are a different story. Those people are sometimes careless.)

If the power won't come back. What model of airliners can actually glide all the way to ground? I watched this at movie once. This would be the safest?

I often ride budget airliner with only 1 engine at either side. So 2 engines at either side is better? What is the safest airliner model with many redundancies?

 

[Klystron]

The airlines select aircraft to fly routes based on many factors -- expected number of passengers, expected cargo, amount of fuel required to fulfill the route, available craft at origin airport, etc. One can choose which airline to book even select which flight to book based on the expected airframe but ultimately route fulfillment lies with the airline.

Suggestions:

1. Install a decent flight simulator on a computer. (select software based on your platform +cost).
2. Take public tours of flight related operations including air shows, air fields, air traffic control centers, open houses; most free.
3. Visit air & space museums. Engage the docents.